subroutine write_transfermatrix(lat,nbranch)

  use bmad
  implicit none

  type (lat_struct) lat
  type (ele_struct) ele
  
  integer lun, i, j
  integer nbranch

  lun = lunget()
  open(unit = lun, file = 'transfer_matrix_file.dat')

  do i=1,lat%branch(nbranch)%n_ele_track
   write(lun,'(/,a,a)')' Element = ', trim(lat%branch(nbranch)%ele(i)%name)
   write(lun,'(4es12.4)')(lat%branch(nbranch)%ele(i)%mat6(j,1:4),j=1,4)
  end do
  close(unit=lun)
return
end